aiaa 2006-4605 thermal protection system sizing and selection … · 2016. 9. 27. · spaceworks...

SpaceWorks Engineering, Inc. (SEIwww.sei.aero

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AIAA 2006-4605Thermal Protection System Sizing and Selection for RLVsUsing the Sentry CodeRevision A10 July 2006

John E. Bradford, PresidentJohn R. Olds, Technical Fellow


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Introduction to SpaceWorks Engineering, Inc. (SEI)

Overview:- Engineering services firm based in Atlanta (small business concern)- Founded in 2000 as a spin-off from the Georgia Institute of Technology- Averaged 130% growth in revenue each year since 2001 - 87% of SEI staff members hold degrees in engineering or science

Core Competencies:- Advanced Concept Synthesis for launch and in-space transportation systems- Financial engineering analysis for next-generation aerospace applications and markets- Technology impact analysis and quantitative technology portfolio optimization

MotivationTool OverviewSpace Shuttle Verification StudyTSTO MSP Case StudyConclusions and Future Work

SpaceWorks Engineering, Inc. (SEI)www.sei.aero

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Presentation Overview


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Motivation


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Develop thermal protection system (TPS) analysis tool that will determine which materials should be used on a launch vehicle and determine how much these materials will weigh

Permit fully-coupled analyses with trajectory and vehicle weights/sizing disciplines in the conceptual/preliminary design phase

Have sufficient fidelity to provide results within +/- 15% of actual weight if constructed and provide sufficient detail to advance design to next stage of development

Tool needs to be fast, robust, and capable of functioning within an automated environment

Objective and Goal


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Design Structure Matrix: All-Rocket SSTO RLV


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Tool Overview


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Created by SpaceWorks Engineering, Inc. (SEI) to support vehicle design studies

Designed from onset to support automated and batch process execution

For use in conceptual and preliminary design of space transportation systems that utilize reusable, non-ablative TPS

Written in modern, object-oriented C++ programming language- Compiled for and executes on PC, Mac OS X, and SGI Unix

Execution time is from 5 to 45 minutes, depending upon setup, optimization level, and analysis resolution

User interface via command-line execution and ASCII input/output files or using Phoenix Integration’s ModelCenter© environment

Sentry: What is it?


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Perform a 1-D unsteady heat transfer analysis with convection, conduction, and radiative effects and an adiabatic backface condition

Consider an unlimited number of candidate TPS materials or “stackups” at each nodal location for a given vehicle geometry and grid

Determine the TPS requirements over the entire vehicle, including the windward and leeward airframe surfaces, chines, wing(s), tail(s), vertical stabilizer(s), and aerodynamic control surfaces

Over the entire vehicle, optimize the thickness of the stackup to minimize weight after factoring in the material properties, temperature limitations, and any manufacturing constraints

At vehicle leading edges, determine the stagnation point conditions using a representative geometry and select an appropriate material based on surface temperatures experienced

Sentry: What can it do?


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X

Material Layer #1

Material Layer #2

Material Layer #3

Material Layer #4

Material Layer #5

Material Layer #6

Backface or Bondline Surface

layer thickness

Exposed Surface

Definition of TPS Stackup


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Input Specifications‘General Parameters’ provided by user include:

Specification method for Qconv interpretation (Direct or Interpolation)Default panel multiplier valueAngle-of-attack override flagVehicle scale factor

‘Component Parameters’ provided by user include:

Initial temperature to initialize airframe components at start of analysisLeading edge specifications (geometric shape, radius, emissivity, etc.)Qconv margin to apply to stagnation and non-stagnation point values

‘Candidate Stackup Parameters' provided by user include:

Total number of candidate stackups defined for vehicle (typically 5-15)Vehicle component assignments for candidate stackupsNumber of material layers in each stackupMaximum height permitted for stackupSizing layer in stackup for optimizerBackface or bondline temperature requirement for stackupMaterial layer(s) ID number, min. gauge, max. surface temperature


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Output Data and ResultsSummary Output File

- Total TPS weight and average weight per unit area for entire vehicle- TPS weights and weight per unit area by component- Acreage material fractions by component (e.g. forebody is 25% CRI, 65% TUFI AETB-8, and 10% TUFI AETB-12)- Maximum stagnation and non-stagnation point temperatures encountered

Tecplot© formatted File

- Maximum surface temperature, material/stackup thicknesses (per layer and total), and material type over entire analysis grid

Detailed Grid/Node Data

- Surface temperature history vehicle time at use specified locations on vehicle- Temperature history into material stackup structure versus time (through the thickness temperature profile)


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Convective Heat Rate Generation

SEI-preferred method for obtaining convective heat rate data is via APAS’sSupersonic/Hypersonic Arbitrary Body Program (S/HABP)

Additionally, Sentry utilizes same analysis grid as that generated by APAS

Two methods used for data specification:1) Direct – Generate Qconv based on actual trajectory flight conditions2) Interpolated – Generate database of Qconv over flight envelope that encompasses the actual trajectory flight conditions

For automated execution of Sentry, the second method should be utilized

S/HABP data file provides x, y, z-coordinates at centroids of analysis grid, surface area for each grid node, and Qconv versus flight Mach number, altitude, and angle-of-attack (AOA)


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Database originated at NASA Ames Research Center from TPSXOriginally written in Fortran 77, converted to ‘C’ for improved integration with SentryIncludes property data for over 100 different TPS and structural materialsInteger ID number identifies desired material in databaseProperties include:

Density (ρ)Thermal Conductivity (k)Heat Capacity (Cp)

1-D (temperature) and 2-D (temperature and pressure) linear interpolation algorithms for property data

Material Property Database - TPSX

Reaction Cured Glass (RCG)Conformal Reusable Insulation (CRI)AETB-8, 12, 16, and 20

Common Materials from TPSX Database

Carbon/SiliconCarbide (C/SiC)

Cerachrome-8 and 12

Internal Multiscreen Insulation

Advanced Carbon Carbon (ACC)

LI-900 and LI-2200

Strain Isolation Pad (SIP)

Inconel-617Aluminum-2219

TitaniumSaffil

NextelRohacel Foam

TUFI (Coating and Diffusion Layer)Flexible Reusable Surface Insulation (FRSI)

Reusable Carbon Carbon (RCC)FRCI 12 and 20

RTV-560Advanced Flexible Reusable Surface Insulation (AFRSI)


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For a given TPS panel, solve 1-D unsteady, heat equation:

Fully implicit solver method using Newton-Rhapson iteration- Central finite differencing scheme at interior nodes (FTSS)- Forward/Backward differencing schemes at upper and lower surface nodes (FTFS)

Top tile surface accounts for conduction, convection, and radiation

Currently only has adiabatic backface boundary condition

Boundary Condition’s:

@ x=0

@ x=L

2

2

xT

tT

∂∂

=∂∂ α

04 =+−dxdTkTq sconv εσ

0=dxdT

Heat Transfer Analysis and Solver


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Verification Study


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Space Shuttle Orbiter Model in APAS

Original model provided by NASA Langley Research Center

SEI modifications included addition of cross sections and points to increase number of grid points

Wing was not reconstructed, although thickness of tip lead edge was identified as being less than actual shuttle LE radii (will impact LE temperature predictions)

Windows were ignored and TPS was sized in these areas


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0

5

10

15

20

25

30

0 200 400 600 800 1,000 1,200

Time (s)

100,000

125,000

150,000

175,000

200,000

225,000

250,000

275,000

300,000

0 200 400 600 800 1,000 1,200

Time (s)

Mach Number Altitude

Trajectory: Mach Number and Altitude vs. Time

• Shuttle Orbiter simulation conducted using POST trajectory code


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TPS Candidate Materials Specified to Sentry

RCC, LI-2200, LI-900, FRSIUpper Wing

RCC, LI-2200, LI-900, FRSITail

RCCWing and Vertical Leading Edges

RCC, LI-2200, LI-900Body Flap

RCC, LI-2200, LI-900, AFRSI, FRSIOMS/RCS Pods

RCC, LI-2200, LI-900

RCC, LI-2200, LI-900, AFRSI, FRSI

CANDIDATE MATERIALS

Lower Wing

Fuselage/Body

COMPONENT

LI-2200 and LI-900 minimum gauge thickness of 0.5 inchesAFRSI minimum gauge thickness of 0.41 inchesFRSI minimum gauge thickness of 0.14 inchesRCC assumed to be 0.5 inches thick with Cerachrome-8 backingFor all components, a backface temperature limit of 810 R was imposed


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Temperature (R)

LEEWARD

WINDWARD

FRONTSIDE

Space Shuttle Results – Maximum Surface Temperatures


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Sentry analysis required about 10 minutes of computational timeDifference in total TPS weight approximately 5%Most significant difference appeared on OMS/RCS pods (~50% error, or 600 lb.)Total TPS surface area difference was less than 1% (~100 ft2)

Weight (lb.)

Sentry AnalysisSpace Shuttle (Actual)**

17,910

806

1,167

800

8,443

6,693

17,114Total

734Body Flap

549OMS/RCS Pods

665Tail

8,517Wings

6,649Fuselage / Body

Space Shuttle Results – Component Weights

**Weights do not include gap fillers, bonds, joints, closeouts, thermal barriers, carrier strips, etc.

Still investigating the differences in TPS results for OMS/RCS podsDifference appears to be primarily in material thickness and not typeCurrent thoughts for explanation of differences:

- Shadowing of pods from S/HABP and thus reduced Qconv predictions in this area- Ascent profile could be driver for TPS sizing


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FRONTSIDE

LEEWARD

WINDWARD

Space Shuttle Results – TPS Material Distribution


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TSTO MSP Case Study


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Quicksat (Mated Configuration)


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Key Vehicle Technologies and Features

(6) TBCC engines(4) DMSJ engines with variable inletUHTC SHARP TPS leading edges (nose, cowl, wings, and tails)Gr-Ep Airframe primary and secondary structureCylindrical, non-integral Gr-Ep fuel tanks and Al oxidizer tanksCRI TPS blankets (fuselage, windward)AFRSI blankets (fuselage, leeward and sidewalls)EHA’s (electro-hydraulic actuators) for control surfacesNo OMS engine requirementIntegrated Vehicle Health Monitoring (IVHM) systemsAll-moving vertical tails

Cylindrical, non-integral Al propellant tanksAFRSI TPS blankets over unshielded upper surfaceMPS engine used as OMS engine for deorbit burnOMS deorbit delta-V of 100 ft/s

Closed-Cycle, JP-7/H2O2 rocket enginesPressure-fed, blow-down monopropellant (H2O2) RCSAdvanced avionics for autonomous flight capability

Quicksat Specific

Upperstage Stage Specific

Entire System


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Integrated Quicksat/Upperstage MSP 3-View

Upperstage Space Maneuver Vehicle (SMV)

52.2 ft

Gross Weight – system (lbs): 741,670

Dry Weight – Quicksat (lbs): 167,840

Dry Weight – Upperstage (lbs): 4,275

Mass Ratio – Quicksat: 2.418

Mixture Ratio – Quicksat: 0.390

Length (ft) 123.6

Booster Payload – Upperstage + SMV (lbs): 89,515

Space Maneuver Vehicle – SMV (lbs): 13,090


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0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

500,000

0 200 400 600 800 1,000 1,200 1,400 1,600

Time (s)

Alt

itu

de (

ft)

Staging Maneuver

Transonic Rocket Boost

Transition TBCC to DMSJ

0

5

10

15

20

25

30

0 200 400 600 800 1,000 1,200 1,400 1,600

Time (s)

Mach

Nu

mb

er

Staging Maneuver

Transonic Rocket Boost

Transition TBCC to DMSJ

Mach Number Altitude

Trajectory and Analysis Setup

Sentry Analysis Setup: • Simulation modeled flyout, pullup, and staging maneuver with 2 hour flyback/thermal soak period• Airframe aeroheating analysis started at Mach 1.25, with uniform structure temperature at 560 R• Constant surface emmissivity of 0.8 for all surface regions• Forebody cylindrical nose leading edge radii of 2” used for stagnation calculations• Wing control surfaces deflected upward 5o and downward 15o over entire flight profile for assessment• Constrained forebody to utilize rigid tiles to maintain smooth surface lines for inlet/engine flow


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Quicksat SOV and Sentry Analysis Grid

Vehicle analysis grid consisted of 2,048 individual nodes


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TPS Candidate Materials Specified to Sentry

2.52,860TUFI AETB-8

2.52,860TUFI AETB-12

0.25” + SAFFIL3,360ACC

0.25” + SAFFIL3,460C/SiC

0.25” + SAFFIL4,460UHTC

2.02,000CRI




3.02,000CRI


Maximum Allowable Height (in)Maximum Temperature (R)COMPONENT – Wing Control Surfaces



Maximum Allowable Height (in)Maximum Temperature (R)COMPONENT – Wings and Tails

2.51,660AFRSI

2,860

2,860

Maximum Temperature (R)

8.0

8.0

Maximum Allowable Height (in)

TUFI AETB-12

TUFI AETB-8

COMPONENT - FuselageTUFI tiles included diffusion layer, AETB-8, RTV-560s and SIP

UHTC, C/SiC, and ACC with titanium backface heat sink (not reflected in weight, part of main structure)

Airframe required backfacetemperature not to exceed 760 R

Wings and Tails backfacetemperatures allowed up to 950 R


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Quicksat Results - Maximum Surface Temperatures

LEEWARD

WINDWARD

Temperature (R)

FRONTSIDE


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Quicksat - TPS Material Weight Results

AVG. UNIT WEIGHT

MATERIAL STACKUPCOMPONENT - Tails

12.6 psfACCLeading Edges0.82 psfCRIWindward Side0.82 psfCRILeeward Side

AVG. UNIT WEIGHT

MATERIAL STACKUPCOMPONENT - Wings

12.6 psfACCLeading Edges1.37 psfCRIWindward Side0.82 psfCRILeeward Side

12.6 psfACCNose

TUFI AETB-8 Ceramic Tiles and CRI

AFRSI Blankets and CRI

MATERIAL STACKUP

1.47 psf0.75 psf

AVG. UNIT WEIGHT

Windward Forebody and Aftbody Nozzle

Leeward and Sidewalls

COMPONENT - Fuselage

Conclusions and Future WorkSpaceWorks Engineering, Inc. (SEI)

www.sei.aero

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Summary and Conclusions

SpaceWorks Engineering, Inc. (SEI) has developed a new engineering software tool for aeroheating analysis and TPS sizing. This tool has proven to be fast, robust, and capable of automated execution.

Results of the verification exercise showed good agreement between Sentry TPS weight and temperature predictions and actual data for the Space Shuttle Orbiter

- Region of greatest difference was OMS/RCS pods; Work continuing to better understand this effect

Sentry was successfully incorporated into a multidisciplinary design process and used in an automated fashion for the TPS design of a TSTO combined-cycle MSP concept


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Future Work

Options for future Sentry capabilities being considered and/or implemented include:

1) Ability to specify an isothermal instead of adiabatic backface condition- Permit heat transfer through airframe/tank wall- Less conservative approach, but may be warranted in some cases

2) Incorporate scale-factor output parameter that represents the impact to vehicle outer mold line due to TPS thicknesses

3) Expansion of TPSX property database to incorporate material cost and maintenance data

- Enable alternate optimization variable besides weight through use of Overall Evaluation Criteria

4) Allow for radiative heat transfer to occur on backface of stackup- Handle gap or standoff distance on backside


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www.sei.aero

Business Address:SpaceWorks Engineering, Inc. (SEI)1200 Ashwood ParkwaySuite 506Atlanta, GA 30338 U.S.A.

Phone: 770-379-8000Fax: 770-379-8001

Internet:WWW: www.sei.aeroE-mail: [email protected]

aiaa 2006-4605 thermal protection system sizing and selection … · 2016. 9. 27. · spaceworks...

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